Pushing For 6G SAS

Question: LSI, Dell and Seagate recently6G delivers a 24Gbps connection.
demonstrated a 6G SAS network for the SCSIWe are seeing interest in SAS on a host interface
Trade Association. Was this a significantas a replacement for Fibre Channel in lower-price
milestone?bands. SAS offers better performance at lower
So: This was the first interoperable demonstrationcosts than other technologies, but it's limited by
of a 6Gbps SAS network featuring everycable distances. 3G SAS tops out at about eight
component of the I/O path - server, HBA, SASmeters. With 6G, we're looking at 10-meter
expander and disk drive. It was a validation of thecabling. But the significance here is that we're
development efforts of all three companies tryingdoubling the transfer rate and still getting longer
to bring the most robust storage solution to thedistances. With parallel SCSI, the line lengths got
enterprise industry. It paves the way for 6G SASshorter as the bandwidth went up.
in late 2009.Question: So we could be seeing an entirely new
Question: What makes 6G SAS preferable to 8GSAN solution then?
Fibre Channel or 10 GbE?So: We're seeing interest in 6G SAS as a
So: SAS was not meant to replace either Fibreswitched topology, in blade centers especially.
Channel or iSCSI. It was initially developed as theWe're looking at a switch product for 3G, and
next-generation SCSI, replacing parallel SCSI inwe're moving forward on a product for 6G.
DAS solutions. But the main disadvantage of bothThere's also new interest in SAS as a host
GbE and Fibre Channel is cost. SAS is a cheaperinterface for external storage, primarily as a
interface to implement, and faster too. ASAS-to-SAS interface for external RAID boxes.
standard external connection typically holds fourWe'll still have FC-to-FC and iSCSI-to-SAS, but the
SAS physical layers. Each SAS PHY today isinterest is there for SAS-to-SAS.
3Gbps, which gives you 24Gbps. Upping that to